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- grep <str> <file>
- Search str in file, or in output of a command (use |)
- tail <file>
- Show de last 20 lines from <file>
- tail -f <file>
- Keep file open and show anything added to the file. tail -f
.sh_history (look what a uses is doing on the commandline)
- head -X <file>
- Show first X regels from <file>.
- fold -w 999 <file>
- Each line is max 999 characters long
- strings <file>
- Show only printable characters from <file>
- pg <file>
- Display <file> page by page, using (-)<no> you can
browse, quit to leave the file immedeatelly.
- less <file>
- Vi keys keay be used to navigate through the file
- tr “[:upper:]” “[:lower:]”
tr “[abc]” “[xyz]”
- Transtlate, make all lowercase
replace all a’s with y, all b’s with y and all c’s with z
works from stdin to stdout. All sort of translations can be done
- read var
read -p “Enter value for VAR1: ” VAR1
read VAR1 VAR2
- Read variabele(s) from stdin (keyboard or pipe), with prompt.
- <stat1> | <stat2>
- Pipe, stdout from <stat1> is connected to stdin
<stat2>.
Formatting
- printf “%04dn” 3
- Output: “0003”, if the 0 is omitted there are spaces in front
- printf “%7.3fn 34.3
- Output: “034.200”, the first number specifies the total length of the output string, the second figure the number of digest after the .
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Redirect
- <command> > file
- stdout for command is file (file is created)
- <command> >> file
- stdout for command is file (output is appended to file)
- <command> > file 2>&1
- Connect stderr to stdout, everything goes to file
- <command> < file
- stdin for command is file (default is keyboard)
- <command> << MARKER
input
input
MARKER
- stdin reads until MARKER
- cmd 2>&1 > file | cmd2
- stderr wordt eerst aan stdout gekoppeld (gaat naar pipe) stdout wordt
daarna aan file gekoppeld
- echo >&2 “error”
- redirection can be anywhere in the command, this sends “error” to
stderr.
- exec > file
- redirect output current shell to file (eg for logging)
- exec 3>&-
- Close file-descriptor 3
- exec 3>&2; exec 2> file; exec 2>&3
- Save stderr in file-descriptor 3, connect stderr to file and restore
original stderr
- exec 3< file
- Open file-descriptor 3 to file
- read -u 3 LINE
- Read a line from file-descriptor 3 and store it in variable LINE
- exec < file 3<&0
- Redirect stdin to file and connect file-descriptor 3 to stdin
- read LINE
- Read a line from stdin (connect to file with redirect above) and
store it in LINE
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