#Bash 的 test 命令
test EXPRESSION
# 或
[ EXPRESSION ]
功能：
检查文件类型和比较整数大小。
类型：
Bash 内置命令。
test和[也是一个可执行文件；为了保持 POSIX 标准的兼容性，确保在其他 shell（比如一些极简的或古老的 shell）或者某些特定环境下，test 命令依然可用。
说明：
- 表达式
( EXPRESSION )- EXPRESSION 是 true! EXPRESSION- EXPRESSION 是 falseEXPRESSION1 -a EXPRESSION2- EXPRESSION1 和 EXPRESSION2 都是 trueEXPRESSION1 -o EXPRESSION2- EXPRESSION1 或 EXPRESSION2 是 true
- 字符串判断
-n STRING- STRING 长度不为 0-z STRING- STRING 长度为 0STRING1 = STRING2- STRING1 等于 STRING2STRING1 != STRING2- STRING1 不等于 STRING2
- 整数判断
INTEGER1 -eq INTEGER2- INTEGER1 等于 INTEGER2INTEGER1 -ne INTEGER2- INTEGER1 不等于 INTEGER2INTEGER1 -lt INTEGER2- INTEGER1 小于 INTEGER2INTEGER1 -gt INTEGER2- INTEGER1 大于 INTEGER2INTEGER1 -le INTEGER2- INTEGER1 小于或等于 INTEGER2INTEGER1 -ge INTEGER2- INTEGER1 大于或等于 INTEGER2
- 文件判断
-e FILE- 文件存在-f FILE- 文件存在且是普通文件（regular file）-d FILE- 文件存在且是目录（directory）-b FILE- 文件存在且是块设备文件（block special）-c FILE- 文件存在且是字符设备文件（character special）-p FILE- 文件存在且是命名管道（named pipe）-S FILE- 文件存在且是套接字文件（socket）-h FILE- 文件存在且是符号链接（symbolic link），同-L-L FILE- 文件存在且是符号链接（symbolic link），同-h-r FILE- 文件存在且当前用户有读权限-w FILE- 文件存在且当前用户有写权限-x FILE- 文件存在且当前用户有执行权限-s FILE- 文件存在且大小大于 0-k FILE- 文件存在且设置了 sticky 位-u FILE- 文件存在且设置了 set-user-ID-g FILE- 文件存在且设置了 set-group-ID-O FILE- 文件存在且所属用户 ID 是当前进程的有效用户 ID-G FILE- 文件存在且所属组 ID 是当前进程的有效组 ID-N FILE- 文件存在且自上次读取后已被修改-t FD- 文件描述符 FD 在终端中被打开FILE1 -ef FILE2- FILE1 和 FILE2 相同（具有相同的设备和 inode 编号）FILE1 -nt FILE2- FILE1 比 FILE2 新FILE1 -ot FILE2- FILE1 比 FILE2 旧
#示例
if [ -d "/tmp" ]; then
echo "/tmp 是目录"
fi
if [ -f "/tmp/code" ]; then
echo "/tmp/code 是普通文件"
fi
if [ -c "/dev/null" ]; then
echo "/dev/null 是字符设备"
fi
if [ 10 -gt 5 ]; then
echo "10 大于 5"
fi
if [ 6 -lt 8 ]; then
echo "6 小于 8"
fi
#推荐阅读
#手册
TEST(1) User Commands TEST(1) NAME test - check file types and compare values SYNOPSIS test EXPRESSION test [ EXPRESSION ] [ ] [ OPTION DESCRIPTION Exit with the status determined by EXPRESSION. --help display this help and exit --version output version information and exit An omitted EXPRESSION defaults to false. Otherwise, EXPRESSION is true or false and sets exit status. It is one of: ( EXPRESSION ) EXPRESSION is true ! EXPRESSION EXPRESSION is false EXPRESSION1 -a EXPRESSION2 both EXPRESSION1 and EXPRESSION2 are true EXPRESSION1 -o EXPRESSION2 either EXPRESSION1 or EXPRESSION2 is true -n STRING the length of STRING is nonzero STRING equivalent to -n STRING -z STRING the length of STRING is zero STRING1 = STRING2 the strings are equal STRING1 != STRING2 the strings are not equal INTEGER1 -eq INTEGER2 INTEGER1 is equal to INTEGER2 INTEGER1 -ge INTEGER2 INTEGER1 is greater than or equal to INTEGER2 INTEGER1 -gt INTEGER2 INTEGER1 is greater than INTEGER2 INTEGER1 -le INTEGER2 INTEGER1 is less than or equal to INTEGER2 INTEGER1 -lt INTEGER2 INTEGER1 is less than INTEGER2 INTEGER1 -ne INTEGER2 INTEGER1 is not equal to INTEGER2 FILE1 -ef FILE2 FILE1 and FILE2 have the same device and inode numbers FILE1 -nt FILE2 FILE1 is newer (modification date) than FILE2 FILE1 -ot FILE2 FILE1 is older than FILE2 -b FILE FILE exists and is block special -c FILE FILE exists and is character special -d FILE FILE exists and is a directory -e FILE FILE exists -f FILE FILE exists and is a regular file -g FILE FILE exists and is set-group-ID -G FILE FILE exists and is owned by the effective group ID -h FILE FILE exists and is a symbolic link (same as -L) -k FILE FILE exists and has its sticky bit set -L FILE FILE exists and is a symbolic link (same as -h) -N FILE FILE exists and has been modified since it was last read -O FILE FILE exists and is owned by the effective user ID -p FILE FILE exists and is a named pipe -r FILE FILE exists and the user has read access -s FILE FILE exists and has a size greater than zero -S FILE FILE exists and is a socket -t FD file descriptor FD is opened on a terminal -u FILE FILE exists and its set-user-ID bit is set -w FILE FILE exists and the user has write access -x FILE FILE exists and the user has execute (or search) access Except for -h and -L, all FILE-related tests dereference symbolic links. Beware that parentheses need to be escaped (e.g., by backslashes) for shells. INTEGER may also be -l STRING, which evaluates to the length of STRING. NOTE: Binary -a and -o are inherently ambiguous. Use 'test EXPR1 && test EXPR2' or 'test EXPR1 || test EXPR2' instead. NOTE: [ honors the --help and --version options, but test does not. test treats each of those as it treats any other nonempty STRING. NOTE: your shell may have its own version of test and/or [, which usually supersedes the version described here. Please refer to your shell's documentation for details about the options it supports. AUTHOR Written by Kevin Braunsdorf and Matthew Bradburn. REPORTING BUGS GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT Copyright © 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO access(2) Full documentation <https://www.gnu.org/software/coreutils/test> or available locally via: info '(coreutils) test invocation' GNU coreutils 9.4 April 2024 TEST(1)